Heat-absorbing device



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H. F. GAGE HJ). Gage INVENTOR HEAT ABSORBING DEVICE Filed Jan. 2e, 1923 A TORNEY Patented Dec. 9, 1924.

UNITED STATES PATENT OFFICE.

HENRY PHELPS GAGE, OF CORNING, NEW YORK, ASSIGNOR TO CORNING GLASS WORKS, 0F CORNING, NEW YORK. A CORPORATION 0F NEW YORK.

HEAT-ABSO'RBING DEVICE.

Application filed January 26, 1923. Serial No. 615,174.

To all 'whom t may conce-rn.:

Be it known that I, HENRY Pnianrs GAGE, a. resident of Corning, in the county oi Steuben and State of New York. have invented certain new and useful improvements in l-leat-Absorbing Devices. ot which the following is a specification.

This invention relates to heat-absorbing devices especially adapted Jfor use in connection with projecting apparatus wherein it is desired to reduce as far as possible, the radiant energy contained in a beam projected from a light source onto an object intended to be viewed, or an image of which is to be projected on a. screen. A 'familial' illustration of a device of the character to which this invention may be applied is the moving picture projector in which a com'entrated beam from an artiticial light. source is projected upon an infiammable film. This film absorbs certain of theI radiant energy contained in thel beam 'falling on it, and thereby becomes heated, and unless keptiu rapid motion, will ignite. 'llbeimportance theretore ot' producing adequate illumination by a beam containing as small amount ot' ra diant energy as possible is therefore apparent.

My invention contemplates a selection of material for the light filter, whereby a high energy absorption with a minimum ot light absorption is given to the device. atthe same time, providing for the proper dissipation of heat resulting from the absorption of energy by the elements o't the sys` tern.

Referring to the accompanying drawings which represent a moving picture projector apparatus embodying my invention, a suitable light source l, preferably in the form of an incandescent electric lamp is so located with respect to the mirror 2 and condenser 3, that a concentrated beam of light is thrown on the moving picture ilm et. to illuminate the same for projection by the optical system 5, as controlled by the sluitter 6. All of these elements may be ot the usual and well known construction. In the path of the beam and between the condenser and the film 4, I locate a water cell 7 and a. screen in the form of a glass plate 8. As is well known, a water cell is one centimetro or more in thickness, completely absorbing radiant energy of wave lengths of a greater length than 1.5 microns, without causing appreciable absorption of' radiant energy within the limits of the visible spectrum. Such water cells have heretofore been used in projecting apparatus.

Nearly one-half, however of the tota-l radiant energy contained in the rays falling on the water, pass through it, part of the rays so passing bein linfra-re ra s or so called heat rays, not usen in li nmination but containing energy.

l have t'ound that by causing the concentrated beam not only to pass through such a water cell, but through a screen having high absorption 'tor rays between the end of the visible red (wave length .77 microns) and 1.5 microns (l where the absorption of water become ett'cctive), I am enabled to absorb the maximum energy 'from the beam without too greatly reducing the portion ol' radiant energy within the visible, limits which contribute to luminosity.

A glass suitable 'for the screen `is the Corning glass (i-IQLIJ, the characteristics of which are described in '.lcchnologio paper No. 93 ot the Bureau of Standards.

[n order to avoid light losses by the multiplicity ot' reficcting surfaces introduced by the water cell and the screen, it is desirable that at least one laec o't the screen be in contact with the water, which may be done by making one, or both of the panes of the water cell ot' the desired absorptive glass. However, it may be more convenient to immerse the screen within the water cell itself, as by so doing, the screen may be removed from the path of the projected beam during such times as moving pictures are being projected, and be put into the path ot the bea-m in still picture projection. F or this purpose, the screen may be carried by an arm 9 to permit the desired movement of' the screen into the path of the beam when the film is arrested.

Obviously, a proper circulating system represented by the intake pipe 10, and exit pipe 11, may he supplied for the water cell, in order that the vater therein may be kept cool, in spite of absorption ot energy from the rays, by both the water and the screen.

Having thus described my invention what I claim as new, and desire to secure by Let.- ters Patent is 1. In a light filter, the combination with a water layer having an absorption of wave lengths greater than 1.5 microns, and a It l,

l l i l l 10 the screen being in contact with the liquid.

3. In u lightiilter, the con'lbil'mtion with :1 liquid layer having a selective ubsorptive power for wave lengths longer than 1.5 microns, and u screen having a selective absorptive power for wave lengths from .77 microns to 1.5 microns, the screen being immersed in the liquid.

In testimony whereof, I hereunto sign my name.

HENRY PHELPS GAGE. 

